From 0d9beb5b2eec3ba839faa58a1a775311d9c3376c Mon Sep 17 00:00:00 2001
From: Rupert Swarbrick <rswarbrick@gmail.com>
Date: Wed, 27 May 2020 09:33:49 +0100
Subject: [PATCH 1/3] Silence warning in select.cc
With GCC 9.3, at least, compiling select.cc spits out a warning about
an implausible bound being passed to strncmp. This comes from inlining
IdString::compare(): it turns out that passing std::string::npos as a
bound to strncmp triggers it.
This patch replaces the compare call with a memcmp with the same
effect. The repeated calls to IdString::c_str are slightly
inefficient, but I'll address that in a follow-up commit.
---
passes/cmds/select.cc | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/passes/cmds/select.cc b/passes/cmds/select.cc
index 6e728c16f..c5ef72b1c 100644
--- a/passes/cmds/select.cc
+++ b/passes/cmds/select.cc
@@ -34,7 +34,10 @@ static bool match_ids(RTLIL::IdString id, std::string pattern)
{
if (id == pattern)
return true;
- if (id.size() > 0 && id[0] == '\\' && id.compare(1, std::string::npos, pattern.c_str()) == 0)
+ const char *id_c = id.c_str();
+ if (*id_c == '\\' &&
+ id.size() == 1 + pattern.size() &&
+ memcmp(id_c + 1, pattern.c_str(), pattern.size()) == 0)
return true;
if (patmatch(pattern.c_str(), id.c_str()))
return true;
From 061d1f0c07623d741e56a36e7a3e5cd48da30d5a Mon Sep 17 00:00:00 2001
From: Rupert Swarbrick <rswarbrick@gmail.com>
Date: Wed, 27 May 2020 09:36:33 +0100
Subject: [PATCH 2/3] Minor optimisations in select.cc's match_ids function
- Pass a string argument by reference
- Avoid multiple calls to IdString::str and IdString::c_str
- Avoid combining checks for size > 0 and first char (C strings are
null terminated, so foo[0] != '\0' implies that foo has positive
length)
---
passes/cmds/select.cc | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)
diff --git a/passes/cmds/select.cc b/passes/cmds/select.cc
index c5ef72b1c..f79f979de 100644
--- a/passes/cmds/select.cc
+++ b/passes/cmds/select.cc
@@ -30,22 +30,24 @@ using RTLIL::id2cstr;
static std::vector<RTLIL::Selection> work_stack;
-static bool match_ids(RTLIL::IdString id, std::string pattern)
+static bool match_ids(RTLIL::IdString id, const std::string &pattern)
{
if (id == pattern)
return true;
+
const char *id_c = id.c_str();
- if (*id_c == '\\' &&
- id.size() == 1 + pattern.size() &&
- memcmp(id_c + 1, pattern.c_str(), pattern.size()) == 0)
+ const char *pat_c = pattern.c_str();
+ size_t id_size = strlen(id_c);
+ size_t pat_size = pattern.size();
+
+ if (*id_c == '\\' && id_size == 1 + pat_size && memcmp(id_c + 1, pat_c, pat_size) == 0)
return true;
- if (patmatch(pattern.c_str(), id.c_str()))
+ if (patmatch(pat_c, id_c))
return true;
- if (id.size() > 0 && id[0] == '\\' && patmatch(pattern.c_str(), id.substr(1).c_str()))
+ if (*id_c == '\\' && patmatch(pat_c, id_c + 1))
return true;
- if (id.size() > 0 && id[0] == '$' && pattern.size() > 0 && pattern[0] == '$') {
- const char *p = id.c_str();
- const char *q = strrchr(p, '$');
+ if (*id_c == '$' && *pat_c == '$') {
+ const char *q = strrchr(id_c, '$');
if (pattern == q)
return true;
}
From d681c9df85eba0ab5112aba5c4b9b89af4ad36a2 Mon Sep 17 00:00:00 2001
From: Rupert Swarbrick <rswarbrick@gmail.com>
Date: Tue, 26 May 2020 11:41:32 +0100
Subject: [PATCH 3/3] Pass some more args by reference in select.cc
Before this patch, the code passed around std::string objects by
value. It's probably not a hot-spot, but it can't hurt to avoid the
copying.
Removing the copy and clean-up code means the resulting code is ~6.1kb
smaller when compiled with GCC 9.3 and standard settings.
---
kernel/register.h | 2 +-
passes/cmds/select.cc | 14 +++++++-------
2 files changed, 8 insertions(+), 8 deletions(-)
diff --git a/kernel/register.h b/kernel/register.h
index 3d89386b7..7bbcd1727 100644
--- a/kernel/register.h
+++ b/kernel/register.h
@@ -125,7 +125,7 @@ struct Backend : Pass
};
// implemented in passes/cmds/select.cc
-extern void handle_extra_select_args(Pass *pass, std::vector<std::string> args, size_t argidx, size_t args_size, RTLIL::Design *design);
+extern void handle_extra_select_args(Pass *pass, const std::vector<std::string> &args, size_t argidx, size_t args_size, RTLIL::Design *design);
extern RTLIL::Selection eval_select_args(const vector<string> &args, RTLIL::Design *design);
extern void eval_select_op(vector<RTLIL::Selection> &work, const string &op, RTLIL::Design *design);
diff --git a/passes/cmds/select.cc b/passes/cmds/select.cc
index f79f979de..13ee030a5 100644
--- a/passes/cmds/select.cc
+++ b/passes/cmds/select.cc
@@ -54,7 +54,7 @@ static bool match_ids(RTLIL::IdString id, const std::string &pattern)
return false;
}
-static bool match_attr_val(const RTLIL::Const &value, std::string pattern, char match_op)
+static bool match_attr_val(const RTLIL::Const &value, const std::string &pattern, char match_op)
{
if (match_op == 0)
return true;
@@ -106,7 +106,7 @@ static bool match_attr_val(const RTLIL::Const &value, std::string pattern, char
log_abort();
}
-static bool match_attr(const dict<RTLIL::IdString, RTLIL::Const> &attributes, std::string name_pat, std::string value_pat, char match_op)
+static bool match_attr(const dict<RTLIL::IdString, RTLIL::Const> &attributes, const std::string &name_pat, const std::string &value_pat, char match_op)
{
if (name_pat.find('*') != std::string::npos || name_pat.find('?') != std::string::npos || name_pat.find('[') != std::string::npos) {
for (auto &it : attributes) {
@@ -124,7 +124,7 @@ static bool match_attr(const dict<RTLIL::IdString, RTLIL::Const> &attributes, st
return false;
}
-static bool match_attr(const dict<RTLIL::IdString, RTLIL::Const> &attributes, std::string match_expr)
+static bool match_attr(const dict<RTLIL::IdString, RTLIL::Const> &attributes, const std::string &match_expr)
{
size_t pos = match_expr.find_first_of("<!=>");
@@ -415,7 +415,7 @@ namespace {
};
}
-static int parse_comma_list(std::set<RTLIL::IdString> &tokens, std::string str, size_t pos, std::string stopchar)
+static int parse_comma_list(std::set<RTLIL::IdString> &tokens, const std::string &str, size_t pos, std::string stopchar)
{
stopchar += ',';
while (1) {
@@ -500,7 +500,7 @@ static int select_op_expand(RTLIL::Design *design, RTLIL::Selection &lhs, std::v
return sel_objects;
}
-static void select_op_expand(RTLIL::Design *design, std::string arg, char mode, bool eval_only)
+static void select_op_expand(RTLIL::Design *design, const std::string &arg, char mode, bool eval_only)
{
int pos = (mode == 'x' ? 2 : 3) + (eval_only ? 1 : 0);
int levels = 1, rem_objects = -1;
@@ -971,7 +971,7 @@ PRIVATE_NAMESPACE_END
YOSYS_NAMESPACE_BEGIN
// used in kernel/register.cc and maybe other locations, extern decl. in register.h
-void handle_extra_select_args(Pass *pass, vector<string> args, size_t argidx, size_t args_size, RTLIL::Design *design)
+void handle_extra_select_args(Pass *pass, const vector<string> &args, size_t argidx, size_t args_size, RTLIL::Design *design)
{
work_stack.clear();
for (; argidx < args_size; argidx++) {
@@ -1675,7 +1675,7 @@ struct CdPass : public Pass {
} CdPass;
template<typename T>
-static void log_matches(const char *title, Module *module, T list)
+static void log_matches(const char *title, Module *module, const T &list)
{
std::vector<IdString> matches;